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Swine wastewater treatment by marsh-pond-marsh constructed wetlands under varying nitrogen loads

Poach, M.E., Hunt, P.G., Reddy, G.B., Stone, K.C., Johnson, M.H., Grubbs, A.
Ecological engineering 2004 v.23 no.3 pp. 165
pig manure, wastewater treatment, constructed wetlands, nitrogen, pollution control, marshes, ponds, total suspended solids, chemical oxygen demand, phosphorus, pollution load, North Carolina
The research objective was to investigate the ability of marsh-pond-marsh (m-p-m) constructed wetlands to treat wastewater from a confined swine operation over varying nitrogen loads. Swine wastewater was applied to six, m-p-m wetlands in Greensboro, NC, USA, during two experimental periods, summer and winter. The efficiency of each system to remove the following wastewater constituents was determined: total suspended solids (TSS); chemical oxygen demand (COD); nitrogen (N); phosphorus (P). During the study, the wetlands removed an average 35-51% of TSS, 30-50% of COD, 37-51% of total N, and 13-26% of total P from swine wastewater. For wastewater COD and N, treatment efficiency was significantly lower during the winter experimental period compared to the summer. Treatment efficiency for all constituents tended to decrease with decreasing air temperatures and increasing rainfall amounts. While these m-p-m wetlands treated more N than an equal area of farm land they were not superior in their N treatment ability compared to previously studied continuous-marsh systems.